1. Field of the Invention
This invention relates to a flow regulating apparatus and method and a flow measuring apparatus and method for a porous hydrostatic bearing such as a cylindrical radial bearing.
2. Related Background Art
In order to obtain a predetermined bearing performance, such as rotational accuracy, high load capability and bearing rigidity in a porous hydrostatic bearing, it is required that, when gas at a predetermined pressure is supplied to a porous material, the flow of gas injected per unit area of a bearing surface or the flow of gas passing through the bearing surface be uniform over the entire bearing surface. As such a flow regulation method, the following process has been conventionally conducted. After holes in the porous material have been choked by imbuing the bearing surface with resin to obtain the flow less than a predetermined value, the resin is partially removed by solvent while measuring the flow of gas passing through the bearing surface. Thus, the regulation is performed to achieve a uniform flow. In more detail, the bearing surface is rubbed with a pin having solvent-imbued cotton to gradually recover the flow by dissolving the resin. Such operations are repeated until the desired flow is achieved.
In the prior art method, however, the regulation operation is relied on the operator's experience or intuition, so that the regulation process is conducted by trial and error. Thus, the number of operation steps becomes great and the cost increases. Further, the process entails a manual operation, so that standardization is difficult and variations in quality are great. In the regulation of the flow through a radial bearing surface, the regulating operation is conducted on the inner surface of a cylindrical, porous material, so that the operation condition is even more difficult.
FIG. 1 shows a prior art measuring method of the flow of passing gas. As shown in FIG. 1, the measuring is conducted by manually pushing a measuring pad 130 with a ring-shaped elastic material 2 at its tip against a radial bearing surface 1a of a porous hydrostatic bearing 1.
Reference numeral 1c is a supply path of compressed air and reference numeral 109 is a flow sensor.
In the prior art measuring method of FIG. 1, the elastic material is unstable, so that the measurement value also becomes unstable, and it takes much time to do the measurement. Moreover, since the elastic material 2 is manually pushed, the pushing force is not constant and the deformation of the elastic material varies each time the measurement of the flow is performed. Thus, the prior art method lacks consistency in obtaining the measured values.
Further, in the prior art regulating method, the solvent cannot be uniformly applied to a regulation area, and the application of solvent to a boundary portion between the regulation areas is difficult. It is also difficult to uniformly apply the solvent to the inner surface of a cylindrical porous material.